Characterisation of the non-starter lactic acid bacteria (NSLAB) of Gruyere PDO cheese

The diversity of non-starter lactic acid bacteria (NSLAB) of Swiss Gruyere cheese was studied in three factories over a six-month period. A total of 1099 isolates of NSLAB from raw milk, skimmilk and Gruyere cheese were characterised at both the species and strain level. Over 90% of the isolates were either Lactobacillus casei or L. rhamnosus, and a combined total of 45 genotypes were found. The genotypes from the three factories differed from one another and varied slowly over the six-month period. At one factory, samples from the corresponding raw milk, skimmilk and cheese culture were also analysed. No NSLAB were found in the cheese starter culture. On the contrary, raw milk contained the largest number of different genotypes. The genotypes found in the cheese all came from raw milk.